In many applications it is desirable or even critical that the output shaft of an electric motor be accurately aligned coaxially with the support structure and/or load engaged by the motor. In such applications it has been the practice to machine or otherwise form a rabbit on the endhead casting of the electric motor case coaxially with the shaft that protrudes through the endhead. For enhanced accuracy where such alignment is critical, it has been conventional practice first to assemble the motor, and then to machine the rabbit while locating off of the motor output shaft. Such operations, requiring complex and accurate machining fixtures, are time consuming and expensive.
A general object of the present invention is to provide an electric motor construction having facility for accurate location of a support structure or load coaxially with the motor output shaft that is easy and inexpensive to manufacture. A more specific object of the invention is to provide a motor construction of the described character that eliminates the necessity in the prior art for machining the endhead casting, and in which the endhead member may therefore be of less expensive stamped steel construction.
An electric motor in accordance with a presently preferred embodiment of the invention includes a case having an axially oriented end member or head, a motor output shaft projecting from the end member for coupling to a motor load, and a bearing mounted on the end member for rotatably supporting the shaft. The bearing has a shoulder or extension that extends axially outwardly from the motor case coaxially with the shaft. The bearing extension is constructed and arranged to be engaged by the support structure and/or load coupled to the shaft for locating the same coaxially with the shaft. The bearing, including the extension, is preferably of homogeneously integral unitary construction, such as of lubricant-impregnated porous metal. The bearing is of sleeve-type or, more preferably, self-aligning spherical construction. The end member may be of cast or, more preferably, stamped steel construction. The bearing extension has a radially outwardly facing surface engagable by the load and/or motor support structure. This surface preferably is cylindrical, but could also be square or other shape in suitable applications.